Surface smoothing arrangement



June 10, 1969 DQMBROWSKI ET AL 3,448,504

SURFACE SMOOTHING ARRANGEMENT Sheet Filed Dec. 1, 1966 INVENTOR 7 M Avw ra. AUaaiozd mm June 10, 1969 T, DOMBROWSKI ETAL 3,448,504

SURFACE SMOOTHING ARRANGEMENT Sheet Filed Dec. 1, 1966 INVENTOR June 1969 'r. DOMBROWSKI ETAL 3,448,504

SURFACE SMOOTHING ARRANGEMENT Filed Dec. 1, 1966 Sheet 3 of 4 FIGS N A 4 B 8 4 ATTORNEY June 10, 1969 DOMBROWSK] ET AL 3,448,504

SURFACE SMOOTHING ARRANGEMENT Sheet Filed Dec. 1, 1966 N ENTOR United States Patent Int. Cl. B24b 39/00 US. CI. 29-90 Claims ABSTRACT OF THE DISCLOSURE Two slanted smoothing rolls are pressed from opposite sides into rolling contact with a rotating workpiece and transported in radial direction of the workpiece.

BACKGROUND OF THE INVENTION The present invention is concerned with apparatus for smoothing the surface of a workpiece by a roll rolling on a surface of the workpiece and being pressed against the same, When the pressure at which the roll is pressed against the workpiece is sufliciently high, the surface layer of the workpiece is permanently deformed since the material is stressed beyond the yield point. Minute projections of the surface layer yield under the pressure and flow into the minute valleys of the surface to fill the same so that the surface is leveled, extremely smooth, and extremely glossy.

In accordance with the prior art, smoothing rolls have been used for smoothing cylindrical surfaces of workpieces which rotate in rolling contact with the smoothing rolls.

This method has not been applied to planar surfaces of a workpiece, but the German Patent 897,563 discloses an arrangement in which the planar surface is smoothed by cylindrical rolls which abut with their cylindrical surface on the planar surface of the workpiece and are in line contact with the same. However, in this method, the material is not subjected to such a pressure that the surface layer is stressed beyond the yield point, but the minute projections of the surface are simply compressed, and do not flow into the valleys of the surface layer. While the surface is smoothed, the quality of the rolled surface is inferior to a surface obtained by pressing the smoothing roll at such a pressure against the cylindrical surface that the yield point is exceeded.

This method requires several staggered pressure rolls operating simultaneously on the treated surface, or a single pressure roll which is guided over the workpiece in several strokes and is laterally displaced between the strokes. In both methods, visible marks indicating the change of position of the pressure roll cannot be avoided.

The German Patent 1,093,249, discloses an arrangement in which a planar surface is smoothed by conical pressure rolls which roll on an annular portion of the planar surface. The surface projections are not stressed beyond the yield point, but simply compressed so that the quality is inferior.

Known apparatus for smoothing planar surfaces require very high pressures, but nevertheless do not produce as smooth a surface as can be obtained by a rotary pressure roller in rolling contact with a cylindrical surface and stressing the surface layer beyond the yield point. When pressure is applied, the line contact between the pressure roll and the workpiece surface is transformed into a surface contact. For economic reasons, the pressure rollers should not be too narrow, so that for obtaining a fairly good result, very high pressures are required. Particularly if a thin walled workpiece, such as a brake disc is treated, the danger is present that the workpiece is deformed and distorted so that the treated surface is no longer planar. This excludes the methods from the use on certain workpieces, such as brake discs where not only extreme smoothness of the surface but also precise planar surfaces are of great importance since otherwise the brake flutters.

SUMMARY OF THE INVENTION It is the object of the invention to prevent deformatinon of planar surfaces while the surface layer of the same is stressed by a smoothing roll beyond the yield point,

With this object in view, one embodiment of the invention comprises means for mounting a workpiece for rotation about a first axis; a pair of smoothing rolls having second axes transverse and slanted to the first axis, and engaging with pressure surfaces planar surfaces of the workpiece from opposite sides, preferably on drop shaped pressure areas; supporting means for rotatably suupporting the rolls, and including pressure means for pressing the rolls against the planar faces of the workpiece; and feeding means for moving the supporting means with the rolls transversely to the first axis so that the planar faces are smoothed without deformation while the rolls are in rolling contact with the planar faces of the workpiece.

Preferably the smoothing rolls have cylindrial surfaces bounded by rounded circular edges and have axes slanted a small angle to the planar faces of the workpiece so that the cylindrical surfaces engage the faces only in the region of the respective circular edge so that the pressure areas on the planar faces of the workpiece are drop shaped.

Since the two smoothing rolls are separated only by the thickness of the workpiece between the planar faces, and act on opposite pressure areas of the same, the opposite pressure forces exerted by the rolls compensate each other and no bending force acts on the workpiece.

In the region of the drop shaped pressure areas, the surface layer of the workpiece is pressed beyond the yield point by the highly polished smoothing rolls so that an extremely smooth and glossy surface is obtained.

The feeding means move the smoothing rolls in a position in which the circular edges which engage the faces of the workpiece, are in a leading position so that the circular surface portion treated during each revolution of the workpiece is independent of the width of the smoothing rolls. The diameter of the smoothing roll may be very small. In the slanted position of the smoothing rolls, in which the rounded edge and a small portion ofthe cylindrical surface engage the treated planar faces, the drop shaped pressure areas on the faces are very small so that a very high specific pressure can be produced by comparatively small pressure forces acting on the smoothing rolls for pressing the same against the faces of the workpiece. This is favorable as far as possible deformation of the workpiece is concerned, and bending forces acting on the workpiece are avoided by symmetrically positioning the smoothing rolls so that the opposite pressure areas register and the pressures applied by the smoothing rolls compensate each other.

In the preferred embodiment of the invention, the smoothing rolls are in rolling engagement with supporting rollers which are mounted on scissor-like pressure means on which a hydraulic motor acts. Preferably, the apparatus is suspended for turning movement about a shaft located above the center of gravity so that the smoothing rolls are disposed symmetrically to the plane of symmetry of the workpiece and forces acting only on one side of the workpiece are avoided.

The supporting rollers have end flanges projecting over the ends of the smoothing rollers so that the smoothing rolls can be transported in substantially axial direction thereof toward the axis of the workpiece.

The novel features which are considered as characteristic for the invention are set forth in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of one embodiment of the invention;

FIG. 2 is a side view of the embodiment of FIG. 1;

FIG. 3 is a fragmentary plan view illustrating a detail of the embodiment on an enlarged scale;

FIG. 3a is a fragmentary schematic side view illustrating the pressure area on the workpiece;

FIG. 4 is a fragmentary front view illustrating a detail of the embodiment on an enlarged scale; and

FIG. 5 is a front view illustrating the embodiment of FIG. I mounted on a lathe on which the workpiece is supported.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 5, a lathe has a head stock supporting a shaft 34 driven by V-belts from a motor 32. Shaft 34 carries a chuck for clamping a shaft portion 1a of a flat circular brake disc 1 whose other shaft portion 11) is rotatably supported on the center of the tail stock 31. The carriage 35 carries a transversely movable feeding slide 2 on which the apparatus of the invention is mounted.

Referring now to FIGS. 1 to 4, slide 2 has a nut portion through which a threaded spindle 18 mounted on carriage 35 passes so that slide 2 with the apparatus can be moved in a direction transverse to the axis of workpiece 1 when hand wheel 18a is rotated.

A supporting shaft 8 extends in this transverse direction in the vertical plane of symmetry of the workpiece, and is located in bearing means of two pressure members 6 and 7 which are double-armed levers. The end portions 9 and 10 of pressure members 7 are connected by a hydraulic motor including a cylinder 11, a piston 13, and a piston rod 12. The other arms 9a and 10a support bearing blocks 20 and 20' and cage means 5 and 5 in whose cavities smoothing rolls 3 and 3' are confined, as best seen in FIGS. 1 and 4. Cage means 5 and 5 are prismatic bars secured by screws 5a to the bearing blocks 20 and 20', respectively.

As best seen in FIG. 3, rolls 3 and 3' have cylindrical surfaces 3a and 3b in rolling contact with a pair of sup- I porting rollers 4 and 4 which have shaft portions 14 and 15 mounted in roller bearings of which roller bearing 15a for shaft portions 15 is shown in FIG. 4. The roller bearings are mounted in bearing blocks 20,

The axes A and A of the roller bearings are slanted symmetrically to the plane of symmetry of the workpiece 1 an angle 16 to the opposite planar end faces 1c and 1d of the workpiece 1.

Since the cylindrical smoothing rolls 3 and 3' are in rolling contact with supporting rollers 4 and 4', the axes B and B are slanted at the same angles to the planar end faces 10 and 1d.

During operation of the apparatus, the feeding means 18, 2 move the supporting and pressure means 6, 7, 20, 20', 4, 4 and 5, 5' in the direction of the arrow in FIG. 3 so that the leading circular edges 17, 17 of smoothing rolls 3, 3' are in contact with the planar faces 10 and 1d. Due to the small angle '16 and the rounding off of the leading circular edges, smoothing rolls 3 and 3 abut opposite pressure areas of the planar faces 1c and 10! with pressure surface portions of the cylindrical surfaces 3a and 3b in the region of the rounded off circular edges 17 and 17'. Consequently, the pressure areas on planar surfaces 1c and 1d are drop shaped as schematically shown at 1 in FIG. 3a.

Supporting rollers 4 and 4' have flanges 19 and 19' projecting partly over the trailing end faces of rolls 3 and 3' to move the same forwardly in the direction of the arrow in FIG. 3 during the operation. Consequently, smoothing rolls 3 and 3' are confined against upward or downward movement by the prismatic cage bars 5 and 5, against outward movement by supporting rollers 4 and 4', and against rearward movement by flanges 19 and 19.

The scissor-like pressure members 6 and 7 have bearing means 21 receiving the stationary shaft =8 which is supported on a support 22 on slide 2, as best seen in FIG. 2. Ribs 21a reinforce the pressure members 6 and 7.

OPERATION A workpiece, for example, a thin brake disc '1, is mounted on the lathe for rotation, and rotated by motor 32. Carriage 35 is positioned so that shaft 8 on support 22 is located above the brake disc and substantially in the vertical plane of symmetry of the same. Hand wheel 18a is operated so that slide 2 moves the apparatus to a position in which the leading ends of rolls 3 and 3' are located near the outer periphery of brake disc 1. The hydraulic motor is actuated so that cylinder 11 and piston rod 12 urge lever arms 9 and 10 of pressure members 6 and 7 apart where-by bearing blocks 20 and 20' with cage bars 5 and 5' move toward each other together with supporting rollers 4, 4' and smoothing rolls 3 and 3 until the pressure surfaces of rolls 3, 3' in the region of the rounded off leading circular edges 17, and 17' engage opposite drop shaped pressure areas 11 on the planar end faces 10 and 1d of the brake disc. Due to the fact that supporting means 6, 7, 20, 20, 4, 4', 5, 5 is supported for turning movement on shaft 8, the position of the supporting means is determined by the workpiece 1 so that upon operation of the hydraulic motor, exactly the same pres sure forces act on opposite sides of the workpiece to press supporting rollers 4, 4 against smoothing rolls 3, 3' and the latter against opposite drop shaped pressure areas on the planar end faces of brake disc 1.

When the pressure exerted by the pressure surfaces of rolls 3, 3' is sufficiently high to stress the surface layers of faces 10 and 1d beyond the yield point, hand wheel 18a is turned and feeding slide 20 is moved along a straight path toward the axis of brake disc 1. During such movement, the rotating brake disc rotates smoothing rolls 3, 3 with which the brake disc is frictionally coupled and rolls 3, 3 rotate supporting rollers 4, 4. The motion of feeding slide 2 is transmitted through bearing blocks 20, 20 and flanges 19, 19' to smoothing rolls 3, 3' so that the planar surfaces are made smooth along a spiral shaped path which consists of successive drop shaped pressure areas 1 as shown in FIG. 3a. Since the pressure surfaces of smoothing rolls 3 and 3 are located at opposite points of the planar faces 1c and 1d and are aligned in axial direction of the workpiece, no bending forces are exerted on the thin brake disc, particularly since the supporting means are turnably suspended on shaft 8.

Angle 16 is very small and depends on the desired shape of the pressure area If. The smaller the pressure area If is selected, the smaller can the pressure be which is exerted by hydraulic motor 11, 13 on the pressure members 6 and 7.

It will be understood that each of the elements described above, or two or more together, may also find useful application in other types of surface smoothing arrangements, differing from the types described above.

While the invention has been illustrated and described as embodied in a pair of smoothing rolls having axes symmetrically slanted to planar faces of a rotary workpiece and engaging the same on drop shaped pressure areas, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the specific and generic aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is set forth in the following:

1. Surface smoothing arrangement, comprising, in combination, mounting means for mounting a workpiece having opposite faces for rotation about a first axis transverse to said faces; a pair of smoothing rolls located on opposite sides of said workpiece and having second axes slanted small equal angles to said faces, respectively, and located in a common plane perpendicular to said faces, each roll having at one axial end thereof a circular edge, said edges abutting oppisite pressure areas of said faces of said workpiece with small pressure surfaces, respectively, substantially shorter in radial direction of the workpiece than the same; supporting means supporting said rolls for rotation about said second axes and including pressure means for pressing said circular edges against said faces, respectively, so that said rolls rotate about said second axes and said edges roll on said faces, respectively, while said workpiece rotates about said first axis; and feeding means for moving said supporting means in said plane along a straight path perpendicular to said first axis in a direction in which said circular edges are located at the leading ends of said rolls while the trailing ends of the same are spaced from said faces due to the slant of said second axes so that said faces are smoothed along spiral lines while said pressure surfaces are in rolling contact with said faces.

2. An arrangement as defined in claim 1 wherein said second axes are located in a plane passing through said first axis.

3. An arrangement as defined in claim 1 wherein said smoothing rolls have cylindrical surfaces bounded by rounded off circular edges so that said pressure surfaces are formed at said edges by small portions of said cylindrical surfaces whereby opposite drop shaped pressure areas of said faces are engaged by said pressure surfaces.

4. An arrangement as defined in claim 1 wherein said supporting means include a pair of supporting rollers in rolling contact with said smoothing rolls, and wherein said pressure means rotatably support said supporting rollers and are operable for pressing the same toward each other so that said smoothing rolls are pressed toward each other and against said faces.

5. An arrangement as defined in claim 4 wherein said supporting rollers have end flanges projecting over the trailing ends of said smoothing rolls to prevent axial displacement of said smoothing rolls relative to said supporting rollers.

6. An arrangement as defined in claim 4 wherein said first axis is horizontal; wherein said pressure means have a bearing located in the plane of symmetry of said sup porting rollers and smoothing rolls; and comprising a shaft located in a vertical plane of symmetry of said workpiece and passing through said bearing for mounting said supporting means turnable to a position in which the plane of symmetry of said supporting rollers and smoothing rolls coincides with the vertical plane of symmetry of said workpiece.

7. An arrangement as defined in claim 4 wherein said pressure means include pivotally connected pressure levers having pressure arms carrying said supporting rollers, and a motor acting on said pressure levers for moving said pressure arms toward each other.

8. An arrangement as defined in claim 4 and comprising cage means mounted on said supporting means and having cavities for retaining said smoothing rolls.

9. An arrangement as defined in claim 1 and comprising drive means for rotating said workpiece about said first axis whereby said smoothing rolls are rotated about said second axes.

10. Surface smoothing arrangement as defined in claim 1, comprising drive means for rotating said workpiece about said first axis whereby said smoothing rolls are rotated about said second axes; wherein said smoothing rolls have cylindrical surfaces bounded by rounded off circular edges; wherein said pressure means include pivotally connected pressure levers having pressure arms, bearing blocks on said pressure arms and supporting rollers mounted in said bearing blocks for movement with said pressure arms, and means acting on said pressure members for moving said pressure arms and supporting rollers toward each other, said supporting rollers being in rolling contact with said smoothing rolls for urging the same toward each other and into rolling contact with opposite pressure areas of said planar faces, said supporting rollers having flanges projecting over the trailing ends of said smoothing rolls so that the same move toward said first axis of said workpiece when said supporting means are moved by said feeding means toward said first axis.

References Cited UNITED STATES PATENTS 2,734,255 2/1956 Tack 29-90 1,501,690 7/1924 Strong 29-90 241,750 5/1881 Taber 29-90 62,251 2/1867 Chapman 29-90 2,915,809 12/1959 Egger 29-90 RICHARD H. EANES, 1a., Primary Examiner. 

